let buf_4 = Buffer.from([105, 108]);
console.log(buf_4.toString());
//toString 默认以utf-8编码
let buf_1 = Buffer.from("hello");
console.log(buf_1[0].toString());

// 溢出情况
buf_1[0] = 361; //buff 元素 只能存 max 二进制数 11111111
